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<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>斐波那契数列</title>
</head>
<body>
        <script>
                function recursion(n) {
                  if (n < 0) {
                    return '输入的数字不能小于0';
                  } else if (n == 0) {
                    return 0;
                  } else if (n == 1) {
                    return 1;
                  } else if (n > 1) {
                    return recursion(n - 1) + recursion(n - 2);
                  }
                }
                console.log(recursion(10));
              </script>
              <p><a href="第四章.html">返回上一级</a></p>
</body>
</html>